Catalina Reyes
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PhD
candidate (UBC)
MSc
Zoology (UBC)
BSc (Los Andes University, Colombia)
Contact
Info:
Department of Zoology
University of British Columbia
6270 University Blvd.
Vancouver, British Columbia
Canada, V6T 1Z4
Tel: (604) 822-5799
FAX: (604) 822-2416
reyes@zoology.ubc.ca
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Peripheral chemoreceptors
in reptiles and their role in cardiorespiratory
control
Reptiles encounter hypoxic and hypercapnic
environments on a daily and seasonal
basis (diving, burrows and dormancy).
In order to maintain blood gas homeostasis
under these conditions, adjustments
in both the cardiovascular and respiratory
systems occur. Control systems such
as those incorporating the central
and peripheral chemoreceptors are
responsible for monitoring the level
of blood gases and adjusting ventilation
and perfusion to meet metabolic demands.
Breathing in reptiles appears to be
highly affected by peripheral chemoreceptor
input, while in mammals these receptors
only play a modulating role. In all
vertebrates, aortic and carotid bodies
(peripheral chemoreceptors) associated
with oxygen and CO2/H+ sensing are
characterized by an association of
glomus cells, sustentacular cells
and nerve terminals. The location
and innervation of these structures
varies widely between vertebrate groups.
Structures homologous to the carotid
bodies in mammals have not yet been
localized in reptiles. Few studies
have found several chemoreceptive
sites in the truncal region of turtles.
Indirect evidence suggests that chemoreceptors
in lizards are located in the carotid
arch, but unlike turtles, no other
chemoreceptive area has been investigated
and chemoreceptive function is unknown.
My
research aims to 1) locate and characterize
the ultrastructure, innervation and
putative neurotransmitters of peripheral
chemoreceptors in different groups
of reptiles so that homologies with
those of other vertebrates can be
derived; and 2) establish the role
of different chemoreceptive sites
in ventilatory regulation and cardiovascular
control. I will test whether distinct
populations of chemoreceptors sense
oxygen tension or O2 content and differ
in their regulatory roles. Specifically,
I will ask whether multiple chemoreceptive
sites are advantageous for reptiles
that regulate blood gases by changing
ventilation and/or the degree of cardiac
shunt. My study will examine if O2-sensing
structures are highly conserved among
vertebrates, while the location (multiple
O2-sensing sites) changed so that
a more effective ventilatory or cardiovascular
control can be exerted in animals
with cardiac shunts such as reptiles.
Last
updated:
8 December, 2008
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